Developers increase unit’s size by almost 3,000 square feet

Being able to claim the roof of a luxury residential tower is a major “get” for high-end buyers—and the developers behind 212 Fifth Avenue have created an opportunity for one wealthy purchaser to do just that.

Madison Equities and Thor Equities decided recently to change their plans for the building’s top floors and the coveted roof, to give the owner of the building’s triplex penthouse sole access to that prime outdoor space, instead of having to share it with the residents of a neighboring duplex unit, as originally envisioned.

The result is a penthouse that grew by almost 3,000 square feet, to a total of 16,000 square feet “all given to one individual,” Robert Gladstone, head of Madison Equities, told Mansion Global.

“We want to make it one spectacular, singular, trophy penthouse,” Mr. Gladstone said.

Madison and Thor could be seen as outliers among New York City developers, who in recent months have changed their floorplans to make way for smaller—and less expensive—units in response to a cooling luxury residential market.

Madison and partner Properties Markets Group did just that at another development, 10 Sullivan, a 22-unit building in Manhattan’s SoHo neighborhood. They reconfigured their original $45 million triplex penthouse into two units: a full-floor apartment and a duplex penthouse with an asking price of $28.5 million. The full-floor unit was once priced at $11.5 million but it currently shows as “no longer available” on StreetEasy.

The crown residence at 212 Fifth Avenue has not yet been priced, but if the current price per square foot for a new luxury apartment in Manhattan is any indication, it could be worth more than $40 million. The price per square foot of high-end units in new developments grew by 28% year-over-year in the second quarter of 2016, to $2,577, according to a Manhattan market report by real estate appraisal and consultancy firm Miller Samuel Inc. for Douglas Elliman.

The reconfigured triplex penthouse will occupy the entire 22nd floor—the entry level— along with the 23rd and 24th stories plus the roof terrace, according to Mr. Gladstone.

Penthouse residents “should be able to own the place,” he said.

A portion of the 5,000-square-foot-plus outdoor space will be hidden, the developer said, so private parties can remain private, without unwelcome attention from photographers. The future owner will also be able to build a swimming pool and plant tall trees, for even more privacy.

“None of this would be true if we had two units” sharing the roof, Mr. Gladstone said.

The developers at 212 Fifth Avenue said they expect to start showing the penthouse by the early fall. Town New Development is handling sales and marketing at the 48-residence building, whose amenities include a fitness center, a golf simulator, a screening room and a catering kitchen.

In the meantime, nine units at the neo-Medieval-style tower, which dates to 1912, are already available, ranging from a two-bedroom for $4.7 million to a four-bedroom for $16.6 million, according to StreetEasy. Another 19 residences are already under contract, including one on the 19th floor featuring five bedrooms and six bathrooms for $28.4 million.